TY - JOUR

T1 - In situ control of thermal activation conditions by color for serpentines with a high iron content

AU - Ivanova, Tatiana K.

AU - Kremenetskaya, Irina P.

AU - Novikov, Andrey I.

AU - Semenov, Valentin G.

AU - Nikolaev, Anatoly G.

AU - Slukovskaya, Marina V.

N1 - Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021/11/1

Y1 - 2021/11/1

N2 - Serpentine heat treatment at temperatures of 650–750◦C yields magnesium–silicate reagent with high chemical activity. Precise and express control of roasting conditions in laboratory kilns and industrial aggregates is needed to derive thermally activated serpentines on a large scale. Color change in serpentines with a high iron content during roasting might be used to indicate the changes in chemical activity in the technological process. This study gives a scientific basis for the express control of roasting of such serpentines by comparing the colors of the obtained material and the reference sample. Serpentines with different chemical activity were studied by X-ray diffraction, Mössbauer spectroscopy, and optical spectroscopy. The color parameters were determined using RGB (red, green, blue), CIELAB (International Commission on Illumination 1976 L*a*b), and HSB (hue, brightness, saturation) color models. The color of heat-treated samples was found to be affected by changes in the crystallochemical characteristics of iron included in the structure of the serpentine minerals. The color characteristics given by the CIELAB model were in good coherence with the acid-neutralizing ability and optical spectra of heat-treated serpentines. Thus, in contrast to the long-term analysis by these methods, the control by color palette provides an express assessment of the quality of the resulting product.

AB - Serpentine heat treatment at temperatures of 650–750◦C yields magnesium–silicate reagent with high chemical activity. Precise and express control of roasting conditions in laboratory kilns and industrial aggregates is needed to derive thermally activated serpentines on a large scale. Color change in serpentines with a high iron content during roasting might be used to indicate the changes in chemical activity in the technological process. This study gives a scientific basis for the express control of roasting of such serpentines by comparing the colors of the obtained material and the reference sample. Serpentines with different chemical activity were studied by X-ray diffraction, Mössbauer spectroscopy, and optical spectroscopy. The color parameters were determined using RGB (red, green, blue), CIELAB (International Commission on Illumination 1976 L*a*b), and HSB (hue, brightness, saturation) color models. The color of heat-treated samples was found to be affected by changes in the crystallochemical characteristics of iron included in the structure of the serpentine minerals. The color characteristics given by the CIELAB model were in good coherence with the acid-neutralizing ability and optical spectra of heat-treated serpentines. Thus, in contrast to the long-term analysis by these methods, the control by color palette provides an express assessment of the quality of the resulting product.

KW - Chrysotile

KW - Color difference

KW - Color models

KW - Iron

KW - Muffle furnace

KW - Mössbauer spectroscopy

KW - Optical spectroscopy

KW - Rotary furnace

KW - Serpentine

KW - X-ray diffraction

UR - http://www.scopus.com/inward/record.url?scp=85119298717&partnerID=8YFLogxK

U2 - 10.3390/ma14216731

DO - 10.3390/ma14216731

M3 - Article

AN - SCOPUS:85119298717

VL - 14

JO - Materials

JF - Materials

SN - 1996-1944

IS - 21

M1 - 6731

ER -